1. Field of the Invention
The present invention relates to a stand for supporting a machine and more particularly, to a bracket assembly for a mobile stand for supporting a machine.
2. Description of the Related Art
FIG. 1 shows a conventional mobile stand 1. The stand 1 comprises a beam 2, four legs 3, and two brackets 4. The legs 3 support the beam 2 in horizontal above a flat surface. The two brackets 4 are mounted on the beam 2 at the top to hold a machine such as a circular sawing machine (not shown). Referring to FIG. 2, the beam 2 has two protruding portions 2a and 2b longitudinally arranged in parallel at two sides. The bracket 4 comprises a rectangular body 4a, a front clamping plate 4b, a rear clamping plate 4c, and a spring member 4d. The bracket body 4a has a bottom opening 4e for receiving the beam 2. The front clamping plate 4b is pivoted to the bracket body 4a and attached to one protruding portion 2a of the beam 2. The rear clamping plate 4c is pivoted to the bracket body 4a and attached to the other protruding portion 2b of the beam 2. The spring member 4d is fastened to the bracket body 4a and stopped against the rear clamping plate 4c to force the rear clamping plate 4c downwards.
FIG. 2 shows the front clamping plate 4b and the rear clamping plate 4c clamped on the two protruding portions 2a and 2b of the beam 2. At this time, the circular sawing machine for example is mounted on each bracket 4. When wishing to remove the circular sawing machine from the stand 1, the rear clamping plate 4c of each bracket 4 is turned upwards from the protruding portion 2b of the beam 2, and then the circular sawing machine with the two brackets 4 are removed from the beam 2.
In the aforesaid design, the spring member 4d imparts a downward pressure to the rear clamping plate 4c, holding the rear clamping plate 4c in engagement with the protruding portion 2b of the beam 2. However, the limited spring force of the spring member 4d is insufficient to hold down the bracket 4 on the beam 2 against an unexpected external biasing force, and the circular sawing machine may be forced out of place accidentally during working.
Therefore, it is desirable to provide a bracket assembly for mobile stand that eliminates the aforesaid drawbacks.